Patent GB-434537-A (GB)
Title: Control of power transmission on vehicles
Filed: 1934-03-09
Abstract: 434,537. Hydraulic transmission of power. LEYLAND MOTORS, Ltd., Richmond Road, Kingston-on-Thames, and HAWORTH, H. F., Motor Works, Hough Lane, Leyland, Lancashire. March 9, 1934, No. 7567. [Class 69 (ii)] [See also Groups XXXI and XXXVIII] Control apparatus for vehicles having an hydraulic torque converter and clutch means for putting in action either the torque converter or a direct drive or freeing the engine, comprises a driver's hand-operated switch and a disconnecting " follow-up " switch operated by or with the clutch movement, the driver's switch in its free-engine position closing a contact common to two control circuits one or other of which is completed according as the disconnecting switch is to one side or other of its mid position, both circuits being interrupted in its mid position. Thus, when the clutch has been moved to its free engine or mid position, any movement from that position moves the disconnecting switch correspondingly and completes a circuit to bring the clutch back to mid position, the circuit then being interrupted. One electric control apparatus may control several clutch mechanisms, for instance on the vehicles of a train, each clutch mechanism having separate centring contacts on the disconnecting switch. Fig. 2 shows a known toggle-actuated clutch mechanism which connects an engine shaft 1 either directly with the transmission shaft 2 or to the pump 3 of a torque converter the turbine part of which (not shown), drives the shaft 2 through a one-way clutch. The change from the direct drive shown, in which a disc 5 on the shaft 2 is gripped between the part 6 and the movable plates 4, to the indirect drive is made by moving the plates 4 so as to grip a disc 7 on the sleeve driving the pump 3. The movement is started by a sleeve and a control fork 8 and is completed by a toggle spring 9. The fork 8 is operated by a pneumatic cylinder and piston 10, 11 controlled by electromagnetically actuated valves 21, 22. Each valve, when operated, connects one end of the cylinder to pressure or vacuum, and when released connects the same end to the atmosphere. The piston 11 is provided with a spring detent 12 to assist in keeping the clutch in the free-engine position, and actuates a disconnecting switch 13 so that the movements of the latter correspond with those of the piston. In the arrangement shown diagrammatically in Fig. 1 two driver's switches 25 are provided, one at each end of a vehicle, and also two reversing switches for controlling reversing gear situated between the torque converter and the driving axle. Control circuits are shown for two engines and clutch mechanisms, each of the latter having its own disconnecting switch 13. Only one of the driver's switches is operative at a time, the switch handle being removable and being used to complete contacts 28, 29 as shown at the left of Fig. 1 in which the switch handle is shown in mid position. In this position connection is made from the positive source through 28, 25, 29 to contact bars 32, 31, 33 of each drum switch 13. If each clutch is in its mid position no circuit is made, but if a clutch and its piston 11 move, the switch 13 also moves and brings contact bar 31 or 33 into contact with a contact of valve 21 or 22 which is then actuated to admit power to return the clutch and piston to mid position. If the driver's switch 25 is moved to the left contact bars 37, 36 of switch 13 are energized, valve 21 is actuated and the clutch is moved so as to bring the torque converter drive into operation. The piston movement which brings this about also turns switch 13 until bar 36 leaves the valve contact, the circuit is broken, and valve 21 restores atmospheric pressure to the cylinder. If switch 25 is moved to the right bars 34, 35 are energized, valve 22 is actuated and the direct drive is brought into operation. The reversing switch is inoperative unless the switch 25 is in mid or free-engine position as its circuit includes a contact in the mid position of switch 25. When switch 25 is in mid position movement of switch 26 to the left energizes the magnet of a valve 23 and brings the forward gear into operation. Similarly, movement of the switch 26 to the right energizes the magnet of a valve 24 controlling the reverse gear. A switch 27 closes the circuit of the engine-starting motor but can only do so when the clutch is in either the free-engine or the torque converter position, the switch circuit including a brush bearing on contact bar 32 of switch 13, this bar leaving the brush when the direct drive is in operation.